I'm not sure if you have the same problem, but I repaired our 
Q-switching element on an old Nd:YAG system not that long ago.

Our q-switch was controlled by an electrically driven device called a 
Pockell cell. If I remember right, a large electrical pulse causes a 
change in the birefringence of the crystal windows, which are made of a 
solid material called potassium dideuterium phosphate (I think they 
refer to it as K*DP). In this relatively old laser (circa 1988) we found 
that a fluid inside had dried out. The fluid is only used for refractive 
index matching, and serves no active purpose in the q-switch activity. 
We found good information here:

http://www.clevelandcrystals.com/nmatch.htm

We called the manufacturer and found out we needed decalin. The company 
wanted a few hundred dollars for a few mLs. Instead, we went to Fisher 
Scientific and bought the stuff for a much better price (~$30 for about 
100 mL).

There was a small port on the side of the Pockell cell, and we just used 
a syringe to inject a bit of decalin until the cell was refilled.

After a few other modifications, the laser has worked fine ever since 
(in both free running and q-switch modes).

-Adam Rowland
University of Texas Dept. of Chem.

Christopher Romanek wrote:
> Dear listmembers,
>
> We have a Merchantek (New Wave) UP213 laser ablation system that is in need of repair. Apparently, our q-switch has a lifetime (3 to 5 yrs) that we have exceeded. It uses a liquid crystal that dries out over time. The cost for repairing the unit by the vendor is $10K to $15K.
>
> Has anyone had a similar problem? If so, any insights or advise would be greatly appreciated concerning ways to fix the unit more economically (third party repairs, etc...)
>
> Sincerely,
>
> Chris Romanek
> University of Georgia
>